Refining mineral oil with solvents



Patented Sept. 22, 1936 UNITED STATES q 2,055,428 IKREFINING MINERAL OIL WITH SOLVENTS Richard:Jewell bearborn, Summit, N. J assignor to The Texas Company, New York, N..Y.,-a;cor-

, poration of'Delaware NDrawing". AppIication'October 24, 1932, i I "Serial'No. 639,299

This invention relates -toithei refining ofi mineral oils and-:more particularly to refining petroleummhydrocarbons by solvent iextraction.

The invention broadly contemplatesrefining mineral oil to remove impurities and undesired components by extracting: the oil with a selective solvent in the presence of a liquid materialwhich, whemmixed withthe oil,:renders itlmore susceptible to iextraction =with' l the so1vent.

1o 'More specifically, theLinVerition contemplates extracting the oil with a selective .solvent,- such as: liquid "sulphur dioxide; furfuralg. nitrobenzene, anduthe like, in theipresenceir-of, on in admixture withga light low-boiling and relatively non-visi 5 cous liquid material such :5 as ea llight hydrocarbonl-sliquidsaidaptedito dissolve the oil or the desired components thereof and precipitate the tarry bodies.

A light hydrocarbon precipitating liquid suit- 20 able for the purpose of my invention may comprise natural gasoline or light petroleum naphtha fractions, or the essential constituents of.

such light gasoline or naphtha as, for example, propane, propylene, butane, and the like. In 25 general, it is advantageous to use a light petroleum fraction having a lower boiling range than the naphtha more commonly used as a solvent or diluent, for example, in dewaxing operations of the prior art.

30 Light aromatic hydrocarbon materials may also be employed equally as well as the paraffin hydrocarbons, and it is contemplated that other liquids which are adapted to dissolve the oil, or are miscible therewith, and which tend to pre- 35 cipitate the undesired asphaltic or tarry bodies,

may be employed in the practice of my invention. 7

According to my invention, the oil to be treated is mixed with a light liquid material, for ex- 40 ample, of the nature of propane or butane, which is adapted to dissolve the desirable components of the oil but which tends to precipitate the undesired constituents, such' as the unsaturated and tarry bodies. These undesired constituents 5 may be partially precipitated, or their solubility in the mixture may be so greatly decreased, that they are in a state of incipient precipitation and are, therefore, more readily extracted and separated by the solvent. The oil undergoing treat- 50 ment is thus rendered more susceptible to treatment by the solvent liquid and the extraction of the undesired constituents of the oil is greatly facilitated and accomplished more effectively.

Light hydrocarbons of the nature of propane 55 or butane are of advantage in this connection since they are si ibstantiallycompletely miscible with the oil fractions derived from crude petroleum, and, upon mixing with oils of this nature containing asphaltic or tarry bodies, they effect a substantialprecipitation of these tarry bodies. 5 Theseprecipitated constituents; which may tend to remain suspended in the oil, are thus anore readily dissolved by the liquid sulphur dioxide, furfural, or other solvent liquid used.

The treatment with the solvent liquid may 10 tolloW -the mixing- 0f the oil with: a: light hydrocarbon material, or it may be carried out simultaneously with such mixing; The :light i hydrocarbon 'm'aterial and solvent liquid may be mixed with-oraadded simultaneously to theoiL or they may be' iirstmix'ed togetheran'd the-resulting admixture commingled with the oil to be treated.

My invention is well adapted, for example, to the manufacture of lubricating oils. Lubricating oil fractions usually contain objectionable constituents in the form of aromatic and unsaturated bodies which are readily oxidizable, as well as sulphur-bearing bodies. These objectionable constituents may be largely in the form of tarry constituents which, as mentioned above, are more readily extracted from the oil in the presence of a light liquid of the nature of propane or butane.

At the same time, during this solvent treatment, the naphthenic or low viscosity index constituents of the oil may be extracted so that, by the practice of my invention, I am able to prepare stable lubricating oil fractions of high viscosity index and free from unstable and other objectionable constituents.

In carrying out the invention in connection with the extraction of lubricating oils, the lubricating oil fraction may be mixed or dissolved in about an equal proportion of the light petroleum fraction. The proportions used may be either 40 greater or less, depending upon the'nature of the oil undergoing treatment. This mixture is then mixed with furfural or liquid sulphur dioxide in and light low-boiling material recovered for further use. 7

The treatment may be carried out at any temperature or pressure desired. The temperatures used may range from considerably below normal room temperature to 200 F. or more. The pressure should be adjusted, depending upon the volatility bf theLIi'ght hydrocarbon or other liquid precipitant used; so' as to maintain the latter in a substantially liquefied state during the extrac: tion. Where it is desired to carry out the treat ment atlow temperatures, an-excess quantity of I the volatile precipitant liquid may be added to the oil, or the mixture of oil and solvent undergoing treatment, and be refrigeratively evaporated therefrom in order to produce such cooling.-

In connection with the extraction of ,wax-bearaswell as the ;Wax insubstantially thesame operation. p

I The invention isnot' necessarily limited to the treatment of lubricatingoil fractions butmay also be adapted to the refining and purification of various hydrocarbon or mineral oil fractions, including naphtha, kerosene, etc., as well as various' residual, or distillate fractions or products derived -from petroleum or other sources. It is also applicable to the treatment and purification of the crude petroleum itself.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

-I'claim:'

1. In the treatment of wax-bearing mineral lubricating oil containing asphaltic bodies, the

method of simultaneously removing asphaltic bodies and Wax constituents comprising mixing the oil with a light petroleum fraction comprising phur dioxide in proportions such that at a temperature of the order of 0 F. asphaltic bodies and wax constituents are precipitated from the cold mixture, cooling the mixture to a temperature of the order of 0. F. to precipitate said asphalt and wax, and. removing :the precipitated material therefrom. My a 2. In the treatment of wax-bearing mineral, lubricatingmoil containing asphaltic bodies, the method vof simultaneously removing asphaltic bodies andwax constituents comprising mixing the oil with propane and liquid sulphur dioxide in proportions :such that at a temperature of the order of ,0. F. asphaltic bodies and Wax constituents are precipitated from the cold mixture, cooling the mixture to atemperature of the order of 0 F. to precipitate said asphalt and wax, and removing the precipitated material therefrom. R. J. DEARBORN. 

